Encapsulation of Liquids

ABSTRACT

A liquid filling apparatus for filling capsules formed by joining two films carried on cylindrical surfaces of respective drums that are arranged in parallel to define a nip comprises two members ( 150,152 ) having an arcuate tapering cross-section so as to be positionable in such a nip defined by two such drums having a predetermined diameter. Each of the two members has opposed arcuate surfaces that, in use, face the cylindrical surfaces of the respective drums. The arcuate surfaces are provided with apertures through which, in use, a pressurised gas is emitted to provide a gas barrier to prevent a filling liquid supplied into the nip between said members from escaping past the arcuate surfaces.

FIELD OF THE INVENTION

The invention relates to methods and apparatus used in forming liquid filled capsules.

BACKGROUND TO THE INVENTION

WO 97/35537 (BioProgress Technology Limited) discloses methods and apparatus for use in forming liquid filled capsules made of a material such as BioProgress XGel film. Referring to FIG. 1, two drums 14, 16 are disposed in parallel and define a nip 18 therebetween. Each drum defines an array of half-capsule shaped cavities (not shown). The drums are rotated about their respective axes of rotation at a fixed synchronous speed and are angularly aligned such that the half-capsule cavities align as they pass downwardly through the nip 18.

Separate, continuous lengths of XGel film 20,22 are fed over the drums and thermoformed on the drum surface. This produces respective films defining half-capsules. The films 20,22 are brought together in the nip and the opposed surfaces stuck together with an adhesive or by applying a solvent to the surfaces so that they adhere to each other as a result of the adhesive action of the partially solvated surfaces. This produces a single continuous sheet of film containing an array of capsules.

As the two films 20,22 are brought together, the capsules are filled by means of an injection unit (not shown). The injection unit is located in the nip 18 and is fed with liquid from a reservoir, which is typically located above the unit. The injection unit comprises an array of injectors that are aligned with the cavities in the drums 14,16 so that there is an injector for each row of capsules. As the capsules are formed, the respective injectors inject a predetermined dose of liquid into the capsules.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved method and apparatus for filling liquid filled capsules and/or an alternative to existing methods and apparatus.

The invention provides a liquid filling apparatus for filling capsules formed by joining two films carried on cylindrical surfaces of respective drums that are arranged in parallel to define a nip therebetween, said apparatus comprising two members having an arcuate tapering cross-section so as to be positionable in a said nip defined by two said drums having a predetermined diameter, each said member having opposed arcuate surfaces that, in use, face the cylindrical surfaces of the respective drums and said arcuate surfaces being provided with apertures through which, in use, a pressurised gas is emitted to provide a gas barrier to prevent a filling liquid supplied into the nip between said members from escaping past said arcuate surfaces.

The invention also includes a liquid filling apparatus for filling capsules formed by joining two films carried on cylindrical surfaces of respective drums in a nip defined by said drums, said liquid filling apparatus comprising two wedge members positionable in a said nip defined between two said drums, in use, said wedge members being positioned in opposed spaced apart relationship to define a filling space therebetween, and means for providing a pressurised gas barrier for preventing the escape of filling liquid from said filling space past respective faces of said wedge members that, in use, face the said cylindrical surfaces of said drums.

The invention also includes apparatus for forming liquid filled capsules, said apparatus comprising:

-   -   a first rotatable cylinder and a second rotatable cylinder, at         least one of said cylinders defining an array of cavities and         each having an axis of rotation, said cylinders being arranged         in parallel spaced apart relation to define a nip extending         generally parallel to said axes of rotation;     -   a first blocking member and a second blocking member positioned         in said nip in opposed spaced apart relation so as to define a         filling space therebetween, each said blocking member having a         first arcuate surface facing said first cylinder and a second         arcuate surface facing said second cylinder and each said         arcuate surface having a plurality of openings defined therein;     -   a device for supplying filling liquid into said filling space;         and     -   a pressurised gas supply connected with said openings for         supplying pressurised gas to said openings to provide respective         gas barriers for preventing the escape of filling liquid from         said filling space past said arcuate surfaces.

The invention also includes a method of liquid filling capsules formed by joining two films carried on cylindrical surfaces of respective drums in a nip defined between the drums, said method comprising providing two wedge members in said nip spaced apart so as to define a filling space therebetween, delivering a filling liquid into said filing space such that the capsules are substantially flooded when they are formed and providing pressurised gas barriers to prevent escape of the filling liquid from said filling space past said wedge members.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be well understood, embodiments thereof, which are given by way of example only, will now be described with reference to the drawings, in which:

FIG. 1 is a schematic representation of a known encapsulation apparatus;

FIG. 2 if a schematic representation of an encapsulation apparatus comprising a first embodiment of liquid filling apparatus according to the invention;

FIG. 3 is a perspective view of the liquid filling apparatus of FIG. 2;

FIG. 4 is a schematic representation illustrating the positioning of members of the liquid filling apparatus relative to a film carried on a drum of the encapsulation apparatus;

FIG. 5 is a perspective view of one of the members of the liquid filling apparatus seen from one side;

FIG. 6 is a perspective view of the member of the liquid filling apparatus shown in FIG. 5 seen from the opposite side;

FIG. 7 is a perspective view of a second embodiment of liquid filling apparatus according to the invention;

FIG. 8 is a plan view of the underside of the liquid filling apparatus of FIG. 7; and

FIG. 9 is a front elevation of the liquid filling apparatus of FIG. 7.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring to FIGS. 2 to 6, a first embodiment of a liquid filling apparatus 100 according to the invention will now be described in connection with an exemplary encapsulation apparatus 102 shown in FIG. 2. It is to be understood that the liquid filling apparatus 100 can be used with encapsulation apparatus having a different configuration to that shown in FIG. 2, which is described herein purely by way of example.

In the encapsulation apparatus 102 illustrated in FIG. 2, two rolls 104, 106 of film 108,110 of like material are rotatably supported on spindles 112,114. An associated mechanism (not shown) is provided for feeding film from the rolls to an encapsulation unit 116. The films first pass over respective support rollers 118,120 and then through respective flexographic printing units 122,124 with associated backing rollers 126,128. The printing units supply to a surface of the film accurately metered quantities of solvent for the film material.

The encapsulation unit 116 is based on the encapsulation unit of conventional apparatus and comprises a reservoir 130 containing the liquid to be encapsulated and a pair of similar moulding drums 132,134. The liquid filling apparatus 100 is incorporated into the encapsulation unit in place of the conventional injection unit.

The outer cylindrical face of each moulding drum 132,134 is formed with a plurality of hemispherical elliptical or other suitably shaped indentations 136 arranged in a series of axially extending rows with, for example, six indentations in each row. Vacuum means (not shown) may optionally be included for applying a vacuum inside the drums to assist deformation of the film material. The drums are supported in parallel side by side relationship with a small gap therebetween, and are arranged for coordinated rotation in opposed directions (the left hand drum 132 clockwise, and the right hand drum 134 anticlockwise). The drums are aligned and angularly arranged such that as they synchronously rotate, the respective rows of cavities meet in the nip defined between the drums. The liquid filling apparatus 100 is located in the region of the nip to receive the filling liquid from the reservoir 130.

In use, film 108,110 is supplied at an appropriate rate to the encapsulation unit 116, passing over the support rollers 118,120 and through the printing units 122,124 where solvent is applied to the film surface in an appropriate amount. The films then pass into the nip between the drums 132,134 which synchronously counter-rotate at an appropriate speed. The films deform to line the indentations 136 of one row in each of the drums, possibly assisted by application of a vacuum, forming a series of six pairs of opposed capsule halves containing filling liquid supplied by the liquid filling apparatus. On continued rotation of the drums the pairs of capsule halves are brought together and seal because of the adhesive effect caused by partial solvation of the film surface, producing a row of liquid filled capsules, which are cut from the films. One row of six capsules is produced approximately every 2 seconds. The resulting capsules 138 are collected in a tray 140, and the waste film remaining is disposed of. The capsules are dried and stabilised in a generally conventional manner.

The liquid filling apparatus 100 will now be described in detail with reference to FIGS. 3 to 6. The liquid filling apparatus comprises two wedge members 150,152 that are supported in opposed spaced apart relationship by a support system 154 that comprises an elongate beam 156. The beam 156 is secured to the encapsulation apparatus 100 by means (not shown) such that is positioned above and extends parallel to the nip defined between the moulding drums 132,134.

The wedge members 150,152 have essentially the same construction and so for ease, only the wedge member 152 will be described in detail.

Referring to FIGS. 5 and 6, the wedge member 152 comprises opposed arcuate faces 154 that are connected by opposed planar side faces 156,158. The arcuate faces 154 are configured such that the wedge members 150,152 have an arcuate tapering cross-section to allow them to fit with a small clearance into the nip of moulding drums 132,134 having a predetermined diameter, with the arcuate faces 154 facing the respective cylindrical surfaces of the moulding drums.

Each arcuate face 154 has a lengthways extending relieved portion (best seen in FIG. 6). The relieved portions are configured to provide a space between the arcuate face 154 and the opposed drum cylindrical surface to permit the passage of the film 108,110 therebetween. The positioning of the relieved portions over the longitudinally extending edge regions 160,162 of the film 108 can be seen in FIG. 4.

The relieved portions of the arcuate faces 154 are each provided with a plurality of lengthways extending recesses 164 that are spaced across the relieved portion. In the embodiment shown in FIGS. 3 to 6, the wedge members 150,152 have three recesses 164. It will be understood that the arrangement shown is purely exemplary and the number of recesses selected may be as desired.

The outermost recess 164 (as viewed in FIG. 6) is provided with a line of apertures 166 at spaced intervals along its length. As shown in FIG. 4, apertures 166 are arranged so that they are aligned with the respective edge regions of the film. The apertures 166 are connected by internal passages (not shown) of the wedge member 152 with a pipe 168 (FIG. 3) that is connected with a pressurised gas supply. The gas supply is preferably pressurised nitrogen, which has the benefit of being inert, although, in principle, any suitable gas may be used.

The outermost face 156 of each wedge member 150,152 is provided with a plurality of bearings in the form of rollers 170 that are arranged to run on the cylindrical surfaces of the moulding drums 132,134 outwardly of the edge regions 160,162 of the film 108,110. As shown in FIG. 3, a biassing spring 172 is provided between each wedge member 150,152 and the elongate beam 156. The springs 172 push the wedge members 150,152 into the nip so that the rollers 170 bear against the moulding drums 132,134 to provide a controlled clearance between the arcuate faces 154 and the opposed cylindrical surfaces of the drums.

The innermost face 158 of at least the wedge member 152 is provided with a plurality of apertures 174 (FIG. 6) that are connected to a source of pressurised gas so that a blanket of an inert gas, such as nitrogen, can be provided over the nip. Preferably, there are apertures 174 provided in both wedge members 150,152 and in each case they are connected with the respective pipes 168 in common with the apertures 166. However, in principle, entirely separate gas supplies may be routed to the two sets of apertures 166,174.

Referring to FIG. 3, twin rails 176,178 extend between and are secured to the wedge members 150,152. A support plate 180 is mounted on the rails 176,178. The support plate 180 supports a fishtail nozzle 182 fitted on a pipe 184. The pipe 184 connects the nozzle 182 with the reservoir 130 (FIG. 2). It is to be understood that the arrangement shown in FIG. 2 is purely exemplary and the reservoir 130 does not have to be situated above the liquid filling apparatus 100 as shown. Instead, the filling liquid could be pumped to the nozzle 182 from a reservoir located elsewhere.

At least one of the wedge members 150,152 (in the embodiment the wedge member 150) is provided with an overflow 186 to provide control of the level of the filling liquid supplied into the nip.

In use, when the encapsulation apparatus 100 is switched on, the pressurised gas supply to the pipes 168 is also switched on. Filling liquid is then supplied to the fishtail nozzle 182 via the pipe 184. The liquid supply rate is adjusted to equal or just exceed the rate needed to fill the capsules 138. The filling liquid is received in a filling space that is defined by the cylindrical surfaces of the moulding drums 132,134 and the inner faces 156 of the wedge members 150,152. The supply pressure of the gas is adjusted so that the pressure of the gas in the clearance between the arcuate faces 154 and the cylindrical surfaces of the drums is sufficient to provide a gas barrier that balances the hydrostatic pressure of the filling liquid in the nip and so prevents the escape of filling liquid past the arcuate faces 154. At the same time, the gas supplied through the apertures 174 creates a gas blanket over the filling liquid in the nip and so isolates the liquid from the atmosphere.

The reservoir of filling liquid in the filling space can be maintained at a level just sufficient to fill the capsules as they are formed. In this case, the hydrostatic pressure of the liquid is essentially atmospheric pressure. In some cases, it may be desirable to fill the capsules at a small positive pressure. This possibility is provided by a second embodiment of a liquid filling apparatus 200 according to the invention, which is illustrated in FIGS. 7 to 9. For ease of reference, the liquid filling apparatus will be described as incorporated in the encapsulation apparatus 102, although it is not limited to use with encapsulation apparatus having that configuration.

The liquid filling apparatus 200 comprises two wedge members 202,204 that correspond substantially to the wedge members 150,152. Although not shown, the liquid filling apparatus 200 is provided with bearings and is intended to be pressed into the nip between the moulding drums by biassing means in the same way as the liquid filling apparatus 100. The bearings and biassing means may take the same form as in the first embodiment, or may take any other suitable form.

The liquid filling apparatus 200 differs from the apparatus 100 in that the wedge members 202,204 have a greater lengthways extent and are interconnected by a transverse member 206. The wedge members 202,204 and transverse member 206 are preferably an integral unit, but may be separate members connected together in any convenient way.

The lower end 210 of the transverse member 206 has opposed arcuate faces similar to the arcuate faces 212 of the wedge members 202,204. This is so that it can fit into the nip in the same way as the wedge members. As shown in FIG. 8, an elongate slot 214 is defined in the lowermost edge of the transverse member. Passages 216 are provided to connect the slot 214 with the reservoir 130. As shown in FIGS. 8 and 9, one or more overflows 216 is/are provided in one or both wedge members 202,204.

The operation of the liquid filling apparatus 200 is similar to that of the apparatus 100. Pressurised gas, preferably nitrogen, is supplied to apertures 220 in the arcuate faces 212 via passages 222 to provide a gas barrier between the arcuate faces and the cylindrical surfaces of moulding drums. Liquid is supplied to the nip via the passages 216 and elongate slot 214. Some liquid will flow up over the lower portions 210 of the transverse member 206 to the level of the overflow(s) 216. The pressure of the gas supply is adjusted to just match the hydrostatic pressure in the nip so that liquid cannot escape sideways between the arcuate faces 212 and the cylindrical surfaces of the drums 132,134. If desired, a gas blanket can be created above the lower portions 210 of the transverse member to separate the liquid in the nip from atmosphere.

In order for the liquid filling apparatus 200 to work, there has to be leakage of the filling liquid over the lower portion 210 of the transverse member 206, as indicated by the arrows 224 in FIG. 9. The pressure drop across the lower portion 210 determines the fill pressure in the nip. By appropriate selection of the height of the lower portion and the clearance between it and the film 108,110 on the drum surface, the filling liquid pressure can be regulated. It is believed the height h should be equal to at least two rows of capsules to provide adequate control.

The wedge members of the two embodiments should function as well when the moulding drums 132,134 are stopped as when they are rotating and so the encapsulation apparatus can be stopped with filling liquid in the nip.

The elongate recesses in the arcuate faces 154,212 are desirable to allow the pressurised gas from the apertures 166,220 to spread uniformly. Similar arrays of apertures without the recesses would not work as effectively. Although not shown, it is in principle possible to provide more than one line of apertures 166,220. Similarly, it is possible for the apertures to be other than circular and they may, for example, take the form of elongate slots. However, circular apertures are preferred. It is possible for the recesses that do not contain apertures 166,220 to be replaced by slots 226 that extend right through the wedge members, as shown in FIGS. 7 to 9.

Adjustment of the gas supply to the apertures 166,220 is relatively easy. When the pressure is correct, small bubbles will be seen percolating into the filing liquid at the periphery of the wedge members. If the pressure is too high, the bubbles will be relatively larger and may cause the liquid to froth. Conversely, if the pressure is too low, filling liquid will escape sideways between the arcuate faces 154,212 and the moulding drums.

Nitrogen is the preferred gas for many applications, because it is inert. This is advantageous when filling capsules with fish oils, or some vegetable oils, because such oils can oxidise if they come into contact with air, resulting on an unpleasant rancid taste.

The liquid filling apparatus 100,200 provides the advantage that the nip is kept filled with filling liquid so that the capsules are flooded as they are formed and complete filling should be ensured. The gas barriers are preferably provided between the arcuate surfaces of the wedge members and the edge regions 160,162 of the films 108,110 to ensure that the filling liquid is held in the filling space between the wedge members and does not get between the film and the moulding drums so that the outside of the filled capsules is not contaminated with the liquid. However, although not preferred, the gas barriers may be provided outwardly of the film edges and so impinge on the cylindrical surfaces of the drum.

It will be appreciated that the liquid filling apparatus may be included as an integral part of an encapsulation apparatus, or retrofitted to existing apparatus.

It is to be understood that the liquid filling apparatus is not limited to use with BioProgress XGel film. It may be used in encapsulation apparatus and methods in which any film is joined in a nip between rollers to form liquid filled cavities.

In the described encapsulation apparatus, the moulding drums 132,134 are supported in parallel side-by-side relationship with a small gap therebetween. This is not essential. There does not have to be a controlled gap. As an alternative, the shaft of one moulding drum may be fixed so as to substantially prevent movement in a horizontal plane, while the shaft of the other drum is mounted so as to be movable in that plane. A biassing force is applied to the movable shaft to press the respective moulding drum toward the “fixed” drum. This provides the possibility of varying the force applied to the films in the nip by varying the biassing force and so being able to control the nip-force independently of the thickness of the films.

It will be appreciated that the nozzle 182 does not have to be a fishtail nozzle. Other shaped nozzles, or a plurality of nozzles may be used as desired. In particular, the choice of nozzle(s) may be varied to take account of the characteristics of the filling liquid. 

1. A liquid filling apparatus for filling capsules formed by joining two films carried on cylindrical surfaces of respective drums that are arranged in parallel to define a nip therebetween, said apparatus comprising two members having an arcuate tapering cross-section so as to be positionable in a said nip defined by two said drums having a predetermined diameter, each said member having opposed arcuate surfaces that, in use, face the cylindrical surfaces of the respective drums and said arcuate surfaces being provided with apertures through which, in use, a pressurized gas is emitted to provide a gas barrier to prevent a filling liquid supplied into the nip between said members from escaping past said arcuate surfaces.
 2. Apparatus as claimed in claim 1, wherein said arcuate surfaces of said members are each provided with a plurality of said apertures arranged to define at least one line of apertures.
 3. Apparatus as claimed in claim 1, wherein said arcuate surfaces of said members are provided with at least one recess extending in a lengthways direction of the surface, the respective said apertures being provided in the or at least one said recess of the arcuate surface.
 4. Apparatus as claimed in claim 1, wherein each of said arcuate surfaces has a lengthways extending relieved portion for passage of an edge portion of the respective said film therebeneath, said apertures being provided in the respective said relieved portions.
 5. Apparatus as claimed in claim 1, wherein each said member defines internal passageways for communicating pressurized gas to the respective said apertures.
 6. Apparatus as claimed in claim 1, wherein each said member is provided with bearings that, in use, seat on said cylindrical surfaces of the drums to provide a predetermined clearance between said arcuate surfaces and cylindrical surfaces.
 7. Apparatus as claimed in claim 6, wherein said bearings comprise rollers mounted on side surfaces of said members that extend between said opposed arcuate surfaces.
 8. Apparatus as claimed in claim 1, wherein at least one of said two members is provided with an overflow passageway for the overflow of said filling liquid supplied into said nip between said members.
 9. Apparatus as claimed in claim 1, wherein at least one of said two members is provided with at least one aperture through which, in use, an inert gas can be emitted to provide a gas blanket over the filling liquid in said nip between said members.
 10. Apparatus as claimed in claim 1, further comprising a support for said two members and at least one biasing element for biasing the two members such that, in use, the members are pressed downwards into said nip.
 11. Apparatus as claimed in claim 10, wherein said at least one biasing element comprises respective spring elements bearing against said two members.
 12. Apparatus as claimed in claim 10, wherein said support supports a device through which, in use, filling liquid is delivered into said nip.
 13. Apparatus as claimed in claim 1, wherein said two members are connected by a transverse member having opposed arcuate surface portions arranged to provide a predetermined clearance with said opposed cylindrical surfaces of the drums when, in use, said members are positioned in said nip.
 14. Apparatus as claimed in claim 13, wherein said transverse member defines an elongate aperture through which, in use, filling liquid is delivered into said nip.
 15. Apparatus as claimed in claim 14, wherein said elongate aperture substantially extends from one of said members to the other of said members.
 16. A liquid filling apparatus for filling capsules formed by joining two films carried on cylindrical surfaces of respective drums in a nip defined by said drums, said liquid filling apparatus comprising two wedge members positionable in a said nip defined between two said drums, in use, said wedge members being positioned in opposed spaced apart relationship to define a filling space therebetween, and means for providing a pressurized gas barrier for preventing the escape of filling liquid from said filling space past respective faces of said wedge members that, in use, face the said cylindrical surfaces of said drums.
 17. Apparatus as claimed in claim 16, wherein said means for providing a gas barrier comprises respective openings provided in said faces of said wedge members.
 18. Apparatus as claimed in claim 16, wherein said wedge members are provided with bearing means for bearing on the cylindrical surface of at least one said drum.
 19. Apparatus as claimed in claim 16, further comprising biasing means for, in use, biasing the wedge members downwardly into said nip.
 20. Apparatus as claimed in claim 16, further comprising means for emitting a pressurized gas to form a gas blanket over a filling liquid in said filling space.
 21. Apparatus for forming liquid filled capsules, said apparatus comprising: a first rotatable cylinder and a second rotatable cylinder, at least one of said cylinders defining an array of cavities and each having an axis of rotation, said cylinders being arranged in parallel spaced apart relation to define a nip extending generally parallel to said axes of rotation; a first blocking member and a second blocking member positioned in said nip in opposed spaced apart relation so as to define a filling space therebetween, each said blocking member having a first arcuate surface facing said first cylinder and a second arcuate surface facing said second cylinder and each said arcuate surface having a plurality of openings defined therein; a device for supplying filling liquid into said filling space; and a pressurized gas supply connected with said openings for supplying pressurized gas to said openings to provide respective gas barriers for preventing the escape of filling liquid from said filling space past said arcuate surfaces.
 22. A method of liquid filling capsules formed by joining two films carried on cylindrical surfaces of respective drums in a nip defined between the drums, said method comprising providing two wedge members in said nip spaced apart so as to define a filling space therebetween, delivering a filling liquid into said filing space such that the capsules are substantially flooded when they are formed and providing pressurized gas barriers to prevent escape of the filling liquid from said filling space past said wedge members.
 23. A method as claimed in claim 22, wherein said gas barriers are provided by emitting gas from apertures defined by said wedge members.
 24. A method as claimed in claim 22, further comprising providing a pressurized gas blanket over the filling liquid in said filling space.
 25. A method as claimed in claim 22, comprising providing a predetermined head of filling liquid in said filling space by providing respective clearances of predetermined height and radial extent between respective arcuate surface extending between said wedge members parallel to said cylindrical surfaces and the respective films carried on said cylindrical surfaces and substantially filling said filling space with filling liquid such that said filling liquid reaches an overflow level above said arcuate surface portions.
 26. A method as claimed in claim 22, wherein each said film has longitudinally extending edges and said wedge members are positioned such that the gas barriers are directed at said films inwardly of said edges. 